Multi-pawl ratchet indexer



April 1970 c. G. PETERSON 3,505,890

MULTI-PAWL RATCHET INDEXER Filed Nov. 20, 1968 v 2 Sheets-Sheet 1 40INVENTOR CARL e. PETERSON ATTORNEYS v April 14, 1970 C. G. PETERSONMULTI-PAWL RATCHET INDEXER 2 Sheets-Sheet 2 Filed Nov. 20, 1968 INVENTORCARL G. PETERSON ATTORNEYS United States Patent O 3,505,890 MULTI-PAWLRATCHET INDEXER Carl G. Peterson, Esmond, R.I., assignor to Carl G.Peterson Co., Smithfield, R.I., a corporation of Rhode Island Filed Nov.20, 1968, Ser. No. 777,221 Int. Cl. F16h 27/02 U.S. Cl. 74142 ClaimsABSTRACT OF THE DISCLOSURE A multi-pawl ratchet indexer for closetolerance feeding on any type of roll feed, comprising a ratchet wheelfixed to a shaft, a plurality of pawls extending around the periphery ofthe ratchet wheel, said pawls being arranged with respect to saidratchet teeth so that there is always at least one pawl in alignmentwith the driving edge of said teeth, said pawls being pivotally mountedbetween a pair of spaced plates with means for imparting oscillatorymovement to said plates, whereby to intermittently drive said ratchetwheel with a minimum of backlash, and means normally urging said pawlsinto engagement with said ratchet wheel, said means also functioning tolimit the outward movement of the pawls at a point where the pawlsbarely clear the ratchet wheel.

BACKGROUND OF THE INVENTION This invention relates to feed mechanismsfor stamping presses and the like, as well as other apparatus using aroll feed, and comprises an improvement over US. Patent No. 2,591,993,dated Apr. 8, 1952.

In the aforesaid patent, a ratchet wheel is provided for intermittentlydriving a feed shaft, said ratchet wheel co operating with a series ofpawls extending in a circular path around the peripheray of the ratchetwheel, said pawls having a vernier arrangement with respect to saidteeth wherein a minimum of slippage of backlash exists. It has beenfound desirable, however, particularly in highspeed operations, toprovide positive stop means for limiting the outward movement of thepawls, and particularly to limit said outward movement to a point wherethe pawl just barely clears the teeth of the ratchet wheel. The failureto include such means in the aforesaid patented structure has renderedsuch structure unsatisfactory for high-speed applications and hasfurther resulted in excessive wear on the spring means that normallyurge the pawls toward the ratchet teeth.

SUMMARY OF THE INVENTION It is therefore a primary object of the instantinvention to provide stop means for limiting the outward movement of thepawls in an indexer of the type shown in the aforesaid U.S. Patent No.2,591,993.

It is a further object of this invention to provide means thatsimultaneously function as a limit stop for outward movement of thepawls and as a part of the means that normally urge the pawls inwardlytoward the ratchet teeth.

Another object is the provision of a multi-pawl ratchet indexer that iscapable of operating at much higher speeds than prior art indexers ofthis type.

Other objects, features and advantages of the invention will becomeapparent as the description thereof proceeds when considered inconnection with the accompanying illustrative drawings.

DESCRIPTION OF THE DRAWINGS In the drawings which illustrate the bestmode presently contemplated for carrying out the present invention:

FIG. 1 is a side elevational view of an indexer embodying the instantinvention with the major portion of the front face plate removed forpurposes of illustration;

3,505,890 Patented Apr. 14, 1970 FIG. 2 is an end elevational viewthereof;

FIGURE 3 is an enlarged fragmentary view showing the pawls and ratchetwheel;

FIG. 4 is an enlarged perspective detail of one of the pawls;

FIG. 5 is an enlarged perspective detail of the stop pin;

FIG. 6 is an enlarged exploded perspective view of the hub and ratchetwheel assembly;

FIG. 7 is a sectional view taken on line 77 of FIG. 3;

FIG. 8 is a sectional view taken on line 88 of FIG. 1;

FIG. 9 is a sectional view illustrating a slightly modified form of myinvention; and

FIG. 10 is a perspective detail of one of the collar members embodied inthe modified form of my invention.

DESCRIPTION OF THE INVENTION Referring now to the drawings, there isshown generally at 10 an indexing mechanism for achieving extremelyaccurate intermittent feed of stock from a feed roll of a stampingpress, punch press or the like. It is extremely important in the feed ofsuch stock that the feed be highly accurate and to a close tolerance,thus minimizing stock waste. The mechanism 10 comprises a pair ofidentical face plates 12, 14 constructed of any suitable structuralmaterial, said plates being substantially circular and having alignedextensions 16, 18 receiving a cross rod 20 on which a standard lever arm22 from the stamping press eccentric (not shown) is pivotally mounted,whereby reciprocal movement of the arm 22, in response to rotation ofthe eccentric, results in oscillating movement of the plates 12, 14 as aunit.

The face plates 12, 14 rotatably receive a shaft or hub 24, said shaftbeing maintained in assembled relation with the face plates by means ofa fixed collar 26 and a retaining ring 28, note FIG. 6. Keyed to theshaft 24, as by spline 30 and key 32, is a ratchet wheel 34 having aplurality of ratchet teeth 36 extending around its outer periphery. Aspreviously stated, the shaft or hub 24 is rotatably mounted with respectto face plates 12, 14, but is drivingly engaged to the feed roll shaftshown in broken lines at 38 in FIG. 2. Thus, when ratchet wheel 36 isdriven by the pawl means hereinafter to be described, shaft or hub 24turns therewith and simultaneously drives the feed roll shaft 38 toeffect the desired feed of stock to the stamping press, punch press orsimilar equipment.

As will be seen most clearly in FIGS. 1 and 3, a series of pawls 40 ispivotally mounted on cross studs 42, said cross studs being fixedlyreceived in oppositely disposed bores in face plates 12, 14, as shownmost clearly in FIG. 8. The series of pawls extends circumferentiallyaround the periphery of ratchet wheel 34 and has a ver nier arrangementwith respect thereto, whereby one pawl in the series will always be insubstantial alignment with the driving edge of a ratchet tooth. Thus,backlash is minimized, to the extent that a feed is provided that isaccurate to better than of an inch. Although the invention is operablewith one series of pawls extending around ratchet wheel 34, greateraccuracy can be obtained by having more than one side-by-side series ofpawls, as illustrated in FIGS. 7 and 8. More specifically, when twoside-by-side series of pawls are used, each pair of side-by-side pawlsmay have their driving edge 44 slightly offset with respect to eachother, thus reducing by one-half any backlash that may occur. Expresseddifferently, by having the two side-by-side series of pawls slightlyoffset with respect to each other, a vernier arrangement is providedthat would be the equivalent of having a single series of pawls but withtwice the number of individual pawls. If desired, the two series ofpawls may be in complete alignment with each other, as shown in FIG. 8,thus increasing the strength of the drive, al though not the accuracythereof.

The operation and structure of the indexing mechanism 10, as describedto this point, is identical to that of aforesaid US. Patent No.2,591,993. It has been found desirable, however, to provide novel meansfor limiting outward pivotal movement of the pawls 40, since bycarefully controlling the movement of the pawls, a much greater feedspeed can be effectively obtained. The desired stop means is achieved byutilizing cross pins 46, preferably of nylon, although other suitablematerials could be used, there being a pin 46 located above each pawl 40adjacent to stud 42, but slightly ofi'set therefrom so that the pin 46may impart a moment to the pawl or pawls with which it is in engagement.The pins 46 are received in aligned bores 48 located on the innersurfaces of plates 12 and 14, and it is important to note that thediameter of the bores 48 is substantially larger than the diameter ofpins 46, whereupon the pins are free to move radially with respect tothe center of ratchet wheel 34 within predetermined limits. By the sametoken, the bores 48 are dimensioned so that some degree of lateral orside-by-side play exists between the pins 46 and the plates 12 and 14.Each pin 46 is provided with a pair of circumferential grooves 50 whichare adapted to receive therein a pair of springs 52, each of whichextends in a complete loop around the entire circular series of pins 46,It will therefore be obvious that the springs 52 bias the pins 46radially inwardly; and since the pins are in engaement with the pawls40, the latter are also normally biased inwardly toward ratchet teeth36. The relative diametrical dimensions of bore 48 and pins 46 is suchthat the pins 46, under action of the springs 52, are free to force thepawls radially inward to the complete depth of the ratchet teeth. Theoutward movement of the pawls is limited to a point where the tooth 34of the pawl barely clears the outer edge of the ratchet teeth 36.Actually, the preferred clearance is about of an inch.

It will be understood that where only one series of pawls 40 isemployed, then the pin 46 would necessarily have only one groove 50 andonly one spring 52. Where two series of side-by-side pawls exist, thepins 46 have two grooves 50 and two springs 52, as illustrated. Wheretwo series of pawls exist and the side-by-side pawls of each series areoffset with respect to each other, it has been found desirable to gentlycurve the upper surface of each pawl 40 as shown at 54 in FIGS. 4 and 7.This curvature facilitates tilting of pin 46 when one pawl is in itsdown position and the pawl alongside it is in its up position, asillustrated in FIG. 7. Of course, this curvature is not necessary whereonly one series of pawls is employed, or where side-by-side pawls are incomplete phase with each other, as illustrated in FIG. 8.

The fact that the pins 46 may move laterally is important for tworeasons. First of all, this lateral play distributes the wear on thepins, and, at the same time, this play is necessary to enable the pin totilt when one pawl is down and the pawl alongside it is up, asillustrated in FIG. 7. It will also be noted that some degree ofrotation of the pins 46 will take place during operation of the device,due to vibration and the like. This rotation causes the springs 52 tomove axially, thereby distributing the wear on the springs and henceincreasing the working life of the springs.

In FIGS. 9 and 10, a slightly modified form of my invention is shownwherein a pin 56 is fixedly mounted between plates 12 and 14 in lieu ofthe loosely mounted pin 46. The desired radial movement is achieved bymounting circular collars 58 on the pin 56, with the inner diameter ofthe collars 58 being substantially larger than the outer diameter of pin56. Thus, the radial play which exists between collars 58 and pin 56corresponds to the aforedescribed radial movement of the pins 46 in thebores 48. The collars 58 are provided with a circumferential groove 60for receiving the springs 52 in the same manner as the aforedescribedgrooves 50. In order to maintain the collars 58 properly positioned onpin 56, an

enlarged portion 62 is provided at the center of pin 56, it beingunderstood that said enlarged portion may take the form of a washersecured to the pin or an integral flange provided thereon. Here again,it will be understood that if only one series of pawls is employed, thenonly one collar 58 would be mounted on pin 56, and means would beprovided for properly positioning the single collar 58 so as to maintainit in alignment with the pawls.

It will now be seen that pursuant to driving movement of the arm 22,which would be movement to the left when viewing FIG. 1, the ratchetwheel 34 will be drivingly engaged by one of the pawls 40, said drivingengagement taking place with a minimum of slippage and backlash, due tothe fact that the vernier arrangement of the pawls with respect to theratchet wheel insures virtually instant engagement of the ratchet wheel,no matter what the relative position is between the face plates and theratchet wheel. The pins 46 and their cooperating springs 52 always biasthe pawls inwardly, and the pins 46 simultaneously serve as limit stopsfor controlling the outward movement of the pawls, to a point where theteeth of the pawls barely clear the ratchet teeth, thus enabling thefeed to operate much faster than has heretofore been possible. Also, byutilizing the pins 46 simultaneously as the biasing means and the stopmeans for the pawls, a space saving is effected which enables theindexing mechanism to have maximum compactness.

While there is shown and described herein certain specific structureembodying the invention, it will be manifest to those skilled in the artthat various modifications and rearrangements of the parts may be madewithout departing from the spirit and scope of the underlying inventiveconcept and that the same is not limited to the particular forms hereinshown and described except insofar as indicated by the scope of theappended claims.

What is claimed is:

1. In a multi-pawl ratchet indexer having a pair of spaced parallelplates, means imparting oscillating movement to said plates as a unit, ashaft extending between said plates and freely rotatable with respectthereto, a wheel keyed to said shaft having a plurality of ratchet teethextending around its periphery, a series of pawls pivotally mountedbetween said plates, said pawls being positioned radially outward fromthe periphery of said ratchet 'wheel and extending therearound, theimprovement comprising means mounted radially outward of each pawl andin engagement therewith, said means being radially movable between afirst position wherein rotation of the pawl away from the ratchet teethis limited to a point where the pawl clears the ratchet teeth but isclosely adjacent thereto and a second position wherein the pawl rotatesto engage the ratchet teeth for the complete depth of the latter, andresilient means normally biasing said movable means and hence said pawlsto said second position.

2. In the indexer of claim 1, said movable means comprising a pinextending across said plates, recesses in said plates receiving theopposite ends of said pin, said recesses being dismensioned to permitmovement of said pins between said first and second positions.

3. In the indexer of claim 2, said resilient means comprising a springextending in a complete loop around said pins.

4. In the indexer of claim 3, each of said pins having a grooveextending therearound for receiving said spring.

5. In the indexer of claim 2, said pins ebing laterally movable betweensaid plates.

6. The indexer of claim 1 further characterized in that two side-by-sideseries of pawls extend around the periphcry of said ratchet wheel, saidmovable means comprising a pin extending across said plates, recesses insaid plates receiving the opposite ends of said pin, said recesses beingdimensioned to permit movement of said pins between said first andsecond position, said resilient means comprising a pair of side-by-sidesprings, each extending in a complete loop around said pins with eachspring in substantial alignment with one series of pawls, the outersurface of said pawls that is engaged by said pins'being gently curvedfrom side to side.

7. In the indexer of claim 1, said movable means comprising a fixedcylindrical pin extending across said plates, and a circular collarmounted on said pin, the inner diameter of said collar beingsubstantially larger than the outer diameter of said pin, whereby saidcollar is free to move between said first and second positions.

8. In the indexer of claim 7, said resilient means comprising a springextending in a complete loop around said collars, said collars havingmeans on their outer surface receiving said spring.

9 The indexer of claim 1 further characterized in that two side-by-sideseries of pawls extend around the periphery of said ratchet wheel, saidmovable means comprising a fixed cylindrical pin extending across saidplates, a pair of circular collars mounted on each pin, the innerdiameter of said collars being substantially larger than the outerdiameter of said pin, whereby said collars are free to move between saidfirst and second positions, and means for maintaining one series ofcollars in substantial alignment with one series of pawls, and the otherseries of collars in substantial alignment with the other series ofpawls.

10. In the indexer of claim 9, said resilient means comprising a pair ofside-by-side springs, one extending in a 7 complete loop around oneseries of collars, and the other 1,418,068 5/1922 Collins 745771,948,082 2/1934 Strangeland 74577 2,061,000 11/1936 Michel et a1 741423,086,405 4/1963 Fleming 74-142 3,301,089 1/1967 Wechsler 74568 FRED C.MATTE'RN, JR., Primary Examiner W. S. RATLIFF, JR., Assistant ExaminerUS. Cl. X.R. 74--577

